# battery keeps dieing on my 90 miata **URL:** \ **Category:** NYSpeed Automotive\ **Created:** [February 18, 2010, 7:56pm UTC](https://forums.speedlife.net/t/battery-keeps-dieing-on-my-90-miata/79477 "2010-02-18T19:56:21Z")\ **Posts on this page:** 20\ **Page:** 1
**Author:** ![llink78](https://yyz2.discourse-cdn.com/flex034/user_avatar/forums.speedlife.net/llink78/32/8037_2.png) [@llink78](https://forums.speedlife.net/u/llink78)\ **Post date:** [February 18, 2010, 7:56pm UTC](https://forums.speedlife.net/t/battery-keeps-dieing-on-my-90-miata/79477/1 "2010-02-18T19:56:21Z")
ok so i thought i had a bad cell in my old battery. the car would drive for about 20min sit go to start again and would be dead. once in a while the battery charge light would flash. so went to Autozone today bought new battery. get home from work try to start the car again after JUST driving it battery is dead wont start the car, but the radio/lights all work. WHAT SHOULD I REPLACE NEXT? im thinking the Alt. or should i be looking at something more simple? ---
**Author:** ![Penfold](https://yyz2.discourse-cdn.com/flex034/user_avatar/forums.speedlife.net/penfold/32/5007_2.png) [@Penfold](https://forums.speedlife.net/u/Penfold)\ **Post date:** [February 18, 2010, 8:00pm UTC](https://forums.speedlife.net/t/battery-keeps-dieing-on-my-90-miata/79477/2 "2010-02-18T20:00:34Z")
I am confused, does it die when driving? If it just wont start, get your starter checked. ---
**Author:** ![dawn](https://yyz2.discourse-cdn.com/flex034/user_avatar/forums.speedlife.net/dawn/32/7209_2.png) [@dawn](https://forums.speedlife.net/u/dawn)\ **Post date:** [February 18, 2010, 8:01pm UTC](https://forums.speedlife.net/t/battery-keeps-dieing-on-my-90-miata/79477/3 "2010-02-18T20:01:45Z")
i think he’s saying he drove it, got home. shut it off, went to start again, and nothing. check alt. belt? check alt. ---
**Author:** ![deebo](https://yyz2.discourse-cdn.com/flex034/user_avatar/forums.speedlife.net/deebo/32/5218_2.png) [@deebo](https://forums.speedlife.net/u/deebo)\ **Post date:** [February 18, 2010, 8:03pm UTC](https://forums.speedlife.net/t/battery-keeps-dieing-on-my-90-miata/79477/4 "2010-02-18T20:03:17Z")
alt ---
**Author:** ![llink78](https://yyz2.discourse-cdn.com/flex034/user_avatar/forums.speedlife.net/llink78/32/8037_2.png) [@llink78](https://forums.speedlife.net/u/llink78)\ **Post date:** [February 18, 2010, 8:03pm UTC](https://forums.speedlife.net/t/battery-keeps-dieing-on-my-90-miata/79477/5 "2010-02-18T20:03:51Z")
> [@dawn](#): > > i think he’s saying he drove it, got home. shut it off, went to start again, and nothing. check alt. belt? check alt. yea thx thats what im saying. car sputtered once while driving from the battery being dead ---
**Author:** ![Penfold](https://yyz2.discourse-cdn.com/flex034/user_avatar/forums.speedlife.net/penfold/32/5007_2.png) [@Penfold](https://forums.speedlife.net/u/Penfold)\ **Post date:** [February 18, 2010, 8:04pm UTC](https://forums.speedlife.net/t/battery-keeps-dieing-on-my-90-miata/79477/6 "2010-02-18T20:04:23Z")
alternator ---
**Author:** ![travisn](https://yyz2.discourse-cdn.com/flex034/user_avatar/forums.speedlife.net/travisn/32/5046_2.png) [@travisn](https://forums.speedlife.net/u/travisn)\ **Post date:** [February 18, 2010, 8:06pm UTC](https://forums.speedlife.net/t/battery-keeps-dieing-on-my-90-miata/79477/7 "2010-02-18T20:06:01Z")
have autozone run their diagnostic tool on it. is the battery dead or it wont start? two totally different things its probably a corroded wire going from the battery to starter. ---
**Author:** ![llink78](https://yyz2.discourse-cdn.com/flex034/user_avatar/forums.speedlife.net/llink78/32/8037_2.png) [@llink78](https://forums.speedlife.net/u/llink78)\ **Post date:** [February 18, 2010, 8:13pm UTC](https://forums.speedlife.net/t/battery-keeps-dieing-on-my-90-miata/79477/8 "2010-02-18T20:13:03Z")
> [@travisn](#): > > have autozone run their diagnostic tool on it. is the battery dead or it wont start? two totally different things > > its probably a corroded wire going from the battery to starter. well that would suck since the battery is in the trunk and the Alt in the front 🙂 ---
**Author:** ![travisn](https://yyz2.discourse-cdn.com/flex034/user_avatar/forums.speedlife.net/travisn/32/5046_2.png) [@travisn](https://forums.speedlife.net/u/travisn)\ **Post date:** [February 18, 2010, 8:17pm UTC](https://forums.speedlife.net/t/battery-keeps-dieing-on-my-90-miata/79477/9 "2010-02-18T20:17:00Z")
likely culprit then. check the resistance with an ammeter, should be less than a milliohm or so(.001 ohms) if its not corroded/broken. or just look at the connection at the starter. probably has nothing to do with the alternator as that wire goes from the alt to the fuse box, while the wire from the battery goes straight to the starter then to the fuse box. but first, is the battery actually dead? lights dim etc? dont just throw parts at the car unless you have spares. check voltage at the positive post on the alternator (where the thicker wire bolts to the alternator) and ground while the car is running, should be 14.7 volts if the alternator is charging correctly. ---
**Author:** ![travisn](https://yyz2.discourse-cdn.com/flex034/user_avatar/forums.speedlife.net/travisn/32/5046_2.png) [@travisn](https://forums.speedlife.net/u/travisn)\ **Post date:** [February 18, 2010, 8:23pm UTC](https://forums.speedlife.net/t/battery-keeps-dieing-on-my-90-miata/79477/10 "2010-02-18T20:23:40Z")
quick google search found it might be the ground wire going from the battery to the vehicle. [http://forum.miata.net/vb/showthread.php?t=365374](http://forum.miata.net/vb/showthread.php?t=365374) ---
**Author:** ![llink78](https://yyz2.discourse-cdn.com/flex034/user_avatar/forums.speedlife.net/llink78/32/8037_2.png) [@llink78](https://forums.speedlife.net/u/llink78)\ **Post date:** [February 18, 2010, 8:27pm UTC](https://forums.speedlife.net/t/battery-keeps-dieing-on-my-90-miata/79477/11 "2010-02-18T20:27:24Z")
> [@travisn](#): > > quick google search found it might be the ground wire going from the battery to the vehicle. > > [What Gauge Wire..... - MX-5 Miata Forum](http://forum.miata.net/vb/showthread.php?t=365374) thx but that dosent sound like my problem, and i think the meter should read 14.1 if the Alt is working ---
**Author:** ![travisn](https://yyz2.discourse-cdn.com/flex034/user_avatar/forums.speedlife.net/travisn/32/5046_2.png) [@travisn](https://forums.speedlife.net/u/travisn)\ **Post date:** [February 19, 2010, 2:40am UTC](https://forums.speedlife.net/t/battery-keeps-dieing-on-my-90-miata/79477/12 "2010-02-19T02:40:45Z")
eh close enough. it will vary and i was trying to say check all connections. the guy in that link didnt say what his symptoms were so how do you know it doesnt sound like your problem? just trying to save you time and money mang, if you want to throw parts at it that it doesnt need go right ahead. ---
**Author:** ![Karter](https://avatars.discourse-cdn.com/v4/letter/k/e480ec/32.png) [@Karter](https://forums.speedlife.net/u/Karter)\ **Post date:** [February 19, 2010, 3:06am UTC](https://forums.speedlife.net/t/battery-keeps-dieing-on-my-90-miata/79477/13 "2010-02-19T03:06:13Z")
easy alternator test. start the car, let it idle, pull the battery terminal, if the car dies, you need an alternator. ---
**Author:** ![skylinez07](https://yyz2.discourse-cdn.com/flex034/user_avatar/forums.speedlife.net/skylinez07/32/4993_2.png) [@skylinez07](https://forums.speedlife.net/u/skylinez07)\ **Post date:** [February 19, 2010, 3:10am UTC](https://forums.speedlife.net/t/battery-keeps-dieing-on-my-90-miata/79477/14 "2010-02-19T03:10:18Z")
I had a simlar problem. I just replaced the battery/alternator but it was still dying. come to doing some troubleshooting it was the 80A fuse for the alternator under the hood. It could be as small as that. GL with the fix. ---
**Author:** ![Bull49](https://yyz2.discourse-cdn.com/flex034/user_avatar/forums.speedlife.net/bull49/32/7381_2.png) [@Bull49](https://forums.speedlife.net/u/Bull49)\ **Post date:** [February 19, 2010, 4:12am UTC](https://forums.speedlife.net/t/battery-keeps-dieing-on-my-90-miata/79477/15 "2010-02-19T04:12:23Z")
> [@Just Karter](#): > > easy alternator test. > > start the car, let it idle, pull the battery terminal, if the car dies, you need an alternator. this. ---
**Author:** ![llink78](https://yyz2.discourse-cdn.com/flex034/user_avatar/forums.speedlife.net/llink78/32/8037_2.png) [@llink78](https://forums.speedlife.net/u/llink78)\ **Post date:** [February 19, 2010, 7:49am UTC](https://forums.speedlife.net/t/battery-keeps-dieing-on-my-90-miata/79477/16 "2010-02-19T07:49:49Z")
[http://www.harborfreight.com/cpi/ctaf/displayitem.taf?Itemnumber=90899](http://www.harborfreight.com/cpi/ctaf/displayitem.taf?Itemnumber=90899) this should work fine right? ---
**Author:** ![JayS](https://yyz2.discourse-cdn.com/flex034/user_avatar/forums.speedlife.net/jays/32/15375_2.png) [@JayS](https://forums.speedlife.net/u/JayS)\ **Post date:** [February 19, 2010, 8:22am UTC](https://forums.speedlife.net/t/battery-keeps-dieing-on-my-90-miata/79477/17 "2010-02-19T08:22:30Z")
> [@Just Karter](#): > > easy alternator test. > > start the car, let it idle, pull the battery terminal, if the car dies, you need an alternator. And probably a new ECM because you just fried it. Not a good test on any modern car. ---
**Author:** ![travisn](https://yyz2.discourse-cdn.com/flex034/user_avatar/forums.speedlife.net/travisn/32/5046_2.png) [@travisn](https://forums.speedlife.net/u/travisn)\ **Post date:** [February 19, 2010, 8:25am UTC](https://forums.speedlife.net/t/battery-keeps-dieing-on-my-90-miata/79477/18 "2010-02-19T08:25:30Z")
> [@llink78](#): > > [http://www.harborfreight.com/cpi/ctaf/displayitem.taf?Itemnumber=90899](http://www.harborfreight.com/cpi/ctaf/displayitem.taf?Itemnumber=90899) this should work fine right? yep. just turn it to 20 dcv and go for it. ---
**Author:** ![Fry](https://yyz2.discourse-cdn.com/flex034/user_avatar/forums.speedlife.net/fry/32/7284_2.png) [@Fry](https://forums.speedlife.net/u/Fry)\ **Post date:** [February 19, 2010, 8:51am UTC](https://forums.speedlife.net/t/battery-keeps-dieing-on-my-90-miata/79477/19 "2010-02-19T08:51:38Z")
LOL just replace your damn alternator. It’s toast. ---
**Author:** ![newman](https://yyz2.discourse-cdn.com/flex034/user_avatar/forums.speedlife.net/newman/32/7569_2.png) [@newman](https://forums.speedlife.net/u/newman)\ **Post date:** [February 19, 2010, 9:00am UTC](https://forums.speedlife.net/t/battery-keeps-dieing-on-my-90-miata/79477/20 "2010-02-19T09:00:31Z")
> [@JayS](#): > > And probably a new ECM because you just fried it. Not a good test on any modern car. Nah. You should be able to do this with no problems, I did it with my lotus. :gotme: [Next page](https://forums.speedlife.net/t/battery-keeps-dieing-on-my-90-miata/79477.md?page=2)